Hydrostatic-mechanical power-distribution transmission

Abstract

A hydrostatic-mechanical power-distribution transmission with infinitely variable gear ratio in the hydrostatic branch and several ratios in the mechanical branch, which downstream of the coupling gear has shiftable planetary reduction gears for the purpose of reducing the power contribution of the hydrostatic branch in the starting range.

We claim: 
     
       1. A hydrostatic-mechanical power-distribution transmission, comprising: a housing;   a driving shaft rotatably mounted on said housing;   a driven output shaft in said housing spaced from said driving shaft;   a hydrostatic power unit in said housing operatively connected with said driving shaft,   a first four-shaft coupling gear having first and second output coupler gear shafts and operatively connected with said driving shaft and hydrostatic power unit;   a three-shaft second coupling gear having a third output coupler shaft downstream of said first coupling gear and being formed with: a sun-wheel being in constant driving contact with said second output coupler shaft,   a planetary carrier in driving contact with said first output coupler shaft, and   a hollow wheel connected with said third output coupler shaft of said second coupling gear;   at least one planetary gear on said housing downstream of said second coupling gear operatively connected with said third output coupler shaft and with said driven output shaft, said planetary gear connecting alternatively said first and second output coupler shafts with said driven output shaft and being formed with a respective sun-wheel and with a respective planetary gear carrier; and   coupling means for producing first, second, third, fourth and reverse transmission ranges mounted on said housing between said second coupling gear and said planetary gear, said coupling means comprising: a first clutch connecting said hollow wheel of said second coupling gear with the sun wheel of said downstream planetary gear operatively connected with said driven output shaft providing thereby the first range,   a second clutch connecting the second coupler shaft of said first coupling gear with the sun wheel of said planetary gear connected with said driven output shaft thereby providing the second range,   a third clutch connecting the first coupler shaft of said first coupling gear with the planetary gear carrier of said planetary gear connected with said driven output shaft defining thereby a third range, and   a fourth clutch operatively connected with said second clutch in the fourth range defined by the second coupler shaft connected with the planetary gear carrier of said planetary gear.       
     
     
       2. The power-distribution transmission defined in claim 1 wherein said first four-shaft coupling gear includes first and second planetary gear sets, said first and second coupler shafts being a hollow wheel of said first planetary gear set, said planetary gear carrier of said second planetary gear set and said first coupler shaft being respective sun wheels. 
     
     
       3. The power-distribution transmission defined in claim 1 wherein said planetary gear includes a third gear set and a reversing planetary gear set downstream of said third gear set and formed with a respective planetary gear carrier connected with the driven output shaft and with a respective sun wheel connected with a hollow wheel of said third gear set, said coupling means including first and second brakes, said hollow wheel of the reversing planetary gear set being connected with said housing via said second brake. 
     
     
       4. The power-distribution transmission defined in claim 3 wherein a disconnecting clutch is provided between the hollow wheel of the third set of said planetary gear and the sun wheel of said reversing gear set. 
     
     
       5. The power-distribution transmission defined in claim 3 wherein said brakes are closed by a spring force and opened by power assistance. 
     
     
       6. The power-distribution transmission defined in claim 1 wherein said output driven shaft is provided with a connecting clutch. 
     
     
       7. The power-distribution transmission defined in claim 1 wherein said clutches are spring-loaded, said clutches being opened by power assistance.